Researchers who created a so-called superstrain of H5N1 bird flu say the virus may not be as lethal or as virulent as has been widely suggested.

This week, at a meeting of experts attending the American Society for Microbiology (ASM) in Washington, D.C., Ron Fouchier of the Erasmus Medical Center who led one of two groups that developed the man-made strain of H5N1 told his colleagues that two misconceptions about his work have circulated in the media.

The first is that the strain he generated in the lab was easily spread, Fouchier said. In testing the transmissibility of the virus among ferrets in the lab (ferrets are often used to study flu because the animals are a good model for how humans would respond to the virus), he found that, in fact, not all healthy ferrets that were exposed to the coughs and sneezes of sick animals became infected.

The second misconception, Fouchier said, is that the virus is highly lethal. Ferrets that became infected in the lab didn’t get very sick or die. They did not get as sick as those infected with the commonly circulating version of H5N1. “This virus does not spread like the pandemic or seasonal flu,” he told the experts gathered at the ASM meeting.

In the real world, H5N1 is thought to be highly lethal to humans. Although it infects people uncommonly, it appears to be deadly when it does. Of 587 human cases of bird flu confirmed by the World Health Organization (WHO) since 2003, nearly 60% have died (though some researchers say the actual mortality rate, if you take into account all the cases that don’t get reported, is much lower).

Adding to the confusion surrounding man-made H5N1, Fouchier said, is the fact that the National Science Advisory Board for Biosecurity (NSABB) requested in December that the details of his work — along with those of Yoshi Kawaoke at the University of Wisconsin, whose team independently reported creating H5N1 in the lab — not be published out of fear that it would promote bioterrorism.

Science and Nature, the two prominent science journals that are considering publishing the studies, agreed to abide by the NSABB’s recommendation and have held off publishing anything for now. In the meantime, both Fouchier and Kawaoke have also voluntarily agreed to halt their work until government officials can figure out how best to proceed with the research. Critics of the research also caution that if the virus escaped from the lab, it could trigger a potentially deadly pandemic.

But as Fouchier told the group at the ASM meeting, such responses to man-made H5N1 may be overblown. He told the group:

If one were going to deduce anything [about] the efficiency of spreading, we would have to conclude that this virus does not spread yet like a pandemic or a seasonal influenza virus. The second misconception is that the virus would be highly lethal if it would ever come out. This virus, although it is highly lethal to chickens, and highly lethal if you put it directly down, at high titers, in the lower respiratory tract, it is certainly not highly lethal if ferrets start coughing and sneezing on one another.

Dr. Anthony Fauci, director of the National Institutes of Health’s National Institute of Allergy and Infectious Diseases, agrees that the dangers of the new virus have been exaggerated and has asked the NSABB to reconsider its recommendation.

A WHO panel convened in February to discuss the matter also disagreed with the NSABB, concluding that the papers should be published in their entirety so researchers could learn valuable lessons about how influenza works.

Although naturally circulating H5N1 does not pass easily from person to person, infectious-disease experts are concerned that the virus may acquire that ability through mutations, as it passes between birds and other animals. If a highly transmissible strain of the virus arose, it could precipitate a pandemic flu that would infect millions. But having access to the details of Fouchier’s and Kawaoke’s work could help scientists prepare for such an outcome.

Whether the NSABB will reconsider and allow publication of the studies remains to be seen, but the ongoing debate has highlighted the precarious position of research with so-called dual purposes (good and bad). As adamantly as scientists defend the neutrality of their work — maintaining that their focus is purely on scientific understanding — it is clear that not all such investigations can exist in isolation and that the system for analyzing their safety and suitability for publication needs an overhaul.